I interpret your problem as having 8 different people of which 6 are girls and 2 are boys. That is the set $\{b_1,b_2,g_1,g_2,g_3,g_4,g_5,g_6\}$.
So the number of permutations of the set with the b's together is $7\cdot2\cdot6!$ and the complement then has $8!-14\cdot6!=42\cdot6!=30240$